In a so-called multi-window system for displaying plural windows, windows to be displayed vary according to each user or each usage situation of a user. If plural windows are to be simultaneously displayed, a user is required to perform appropriate operations to display or hide these windows (include minimization and iconization). Particularly, in a small information-processing device, such as a mobile phone, which does not have a pointing device such as a mouse, such an operation is more complicated.
JP-A-10-260810 or JP-A-5-274106 describes a technique for controlling display of plural windows. JP-A-10-260810 describes a technique for changing an arrangement of windows already displayed, based on a number of transitions among plural windows (a movement of a focus). JP-A-5-274106 describes a technique for displaying, when a user divides plural windows into some groups and instructs to display a window, windows belonging to an identical group at the front side of windows belonging to another group as a priority.